Traditionally considered strictly a portrait retouching technique, frequency separation allows you to change the texture of a particular area of an image, while maintaining the color and brightness levels of that area, and vice versa. It’s often used by fashion retouchers to achieve those perfectly smooth skin tones that are free of marks and blemishes; however, it can sometimes be overused, resulting in an unnatural look. Because of this propensity to overdo it with frequency separation, it is one of those photography techniques that has been known to draw impassioned reactions when brought up in certain company. What you almost never hear about frequency separation is that it’s an extremely useful tool for editing landscape photos and, if used tastefully, can dramatically improve a composition.
If you take a look at our example image at the top of the page, you’ll notice Central Park’s iconic Bow Bridge, on a nice, clear winter evening. To capture the ambient, serene quality of the scene, I popped my camera on a tripod, attached a 6-stop LEE ND filter, and settled on a shutter speed of 5 seconds, which gave the water the smooth look that I was going for—almost.
Now, if you would, please turn your attention to the unedited RAW image below, and specifically the bottom, left-hand corner.
This is what I saw at home when I looked at the image on my computer screen—what I thought was perfectly clear water had a huge patch of dirty ice in the bottom left-hand corner of the frame. I tried the Clone and Heal tools in Photoshop just because it’s easy, but no dice; I could not remove the dirty ice without it leaving me with an unnatural, uneven look.
Then I tried cropping, but I just couldn’t get the composition to feel as good to me as it felt uncropped. This, I thought, would be a good time to use frequency separation, to smooth out the texture of that spot in the water, all while maintaining the color and brightness levels for a natural look.
Here’s How I Did It in Photoshop
1. First I brought the image into Photoshop and made a duplicate of the layer (Crtl+J on a PC or Cmd+J on a Mac), which left me with two layers of the same image. I named one of the layers “Color” and the other one “Texture.”
2. Next, I selected the Color layer, and added a Gaussian Blur by selecting Filters > Blur > Gaussian Blur from the drop-down menu. I turned the radius dial up until the area I wanted to remove was devoid of any discernible detail, settling on a value of 30.4.
3. Then, I selected the Texture layer, and went to Image > Apply Image in the drop-down menu. For the blending mode, I selected subtract, because we want to subtract everything from the Texture layer, other than the fine details of the image. In the layer field, I selected the Color layer, which contains the color and light information that we intend to subtract from the Texture layer. When doing frequency separation, you always want to make sure to set the Scale to 2 and the Offset to 128. Once I got it set just like this, I clicked OK.
4. Then, I made sure my Texture layer was on top, and I set the Blend mode to Linear Light.
5. This left me with one layer that contained all of the fine details in the image, and another layer that had all the color and brightness values.
6. And, when both layers are made visible, the two combined make up our original, RAW image. Only now, we can treat the texture of the image separately from the light and color.
7. Then, I created a white layer mask on top of the Texture layer by clicking the Add Layer Mask button shown below.
8. Finally, using a large soft brush set to 50% opacity, I gently brushed out the dirty ice, and you can see before and after, below.
And, as you can see, the dirty ice has been removed from the final image.
I hope you enjoyed this tutorial about using frequency separation to improve your landscape photos. If you have any questions or tips of your own, please be sure to leave them in the Comments section.